1. Field of the Invention
The present invention relates to diesel engines and more particularly to a flexible governor coupling device for use in fuel injector pumps for diesel engines utilizing urethane coupling rings. The invention further relates to a resilient coupling having self confined, high temperature, fuel resistant flexure members.
2. Background of the Art
Diesel engines have been incorporated in a wide variety of motor vehicles including passenger cars and light trucks for many years. Diesel engines have found greater use in recent years because of the advantages of the basic engine design including, lower cost fuels, greater fuel efficiency, lack of complicated wiring and electronic fueling systems, etc. To a great extent diesel engines for use in commercial and heavy duty vehicles have been designed or engineered over time and have performed well.
However, many diesel engines, especially the lighter vehicle versions, have been plagued with problems in recent years. These engines have undergone failures ranging from a simple loss of power to a catastrophic failure of the entire fuel system. These problems have often been attributed to poor design characteristics for the engine as a whole but are not readily understood due to the wide variations in the manifested damage and no post damage analysis by repair facilities.
Diesel engines operate using a close approximation to the Carnot thermodynamic cycle as opposed to the Otto cycle employed by conventional gasoline engines. A diesel engine compresses air in the cylinders to much higher pressures so that the air achieves ignition temperatures for the fuel. The fuel is then injected directly into the cylinders where it is combusted and drives the cylinders. Therefore, no spark plugs are required for this combustion process.
Diesel engines use high pressure multi-staged fuel pumps to inject the fuel directly into the cylinders at the higher cylinder pressures. Since diesel engines function as compression fired systems, there is no spark advance or retard mechanism as in gasoline engines. This function is replaced by the timing of the fuel injection into the cylinders. Therefore, fuel injectors provide two major functions for engine operation. The control of fuel flow rate and the timing of fuel entry.
It has been discovered, however, that fuel flow and timing mechanisms in some fuel injector pumps have design flaws that are responsible in great part for the aforementioned engine failures. This is seen principally in a class of injector pumps produced by the Roosa Master Company of Hartford, Conn. which employs a flexible coupling ring assembly between a rotating governor mechanism and a main injector pump drive shaft. This coupling assembly has been found to have a high rate of failure.
When the flexible coupling for the governor fails, major or even catastrophic damage may result. Such damage occurs because the coupling ring material segments into very small pieces that become lodged in fuel lines and high pressure rotary fuel pump stages creating abnormally high pressures within the pump. This causes severe damage to these parts and any high pressure seals or membranes encountered. This leads to fuel system leaks and general failure. Even if the damage is limited, replacing the coupling ring assembly and associated parts with an assembly of the same design simply creates a probability that the same problem will occur again with potentially more serious results.
What is needed then is a method of constructing or repairing the governor drive linkage so that system failure is avoided and the life span of both the fuel injector pump and the engine are extended. Such a method or apparatus has eluded the prior art developers before the present invention. The prior art solution has been to either periodically rebuild damaged injector pumps or change the engine design to incorporate different governor devices or fuel injector pumps at great expense and not correct problems with existing engines nor take advantage of existing engine development.